自定义 PNG 翻转功能在图像上输出黑色背景

发布于 2024-10-17 12:08:28 字数 582 浏览 5 评论 0原文

我正在使用 PHP GB 库来操作图像。我注意到 GB 库没有附带的一件事是垂直或水平翻转图像的能力。所以我开始为它构建自己的函数。这就是我得到的结果：

function flipImage($image) {
    $width  = imagesx($image);
    $height = imagesy($image);

    $out = imagecreatetruecolor($width, $height);

    for($i = 0; $i < $width; $i++) {
        // Copy the image strip going left to right
        imagecopy($out, $image, $width - $i, 0, $i, 0, 1, $height);
    }

    //$out should now hold our flipped image
    return $out;
}

它按我的预期工作，但由于某种原因，返回的图像 ($out) 具有黑色背景而不是透明背景。

有没有办法让返回的图像像源图像一样具有透明背景？

原文

I'm working with the PHP GB library to manipulate images. One of the thing I noticed doesn't come with the GB library is the ability to flip images either vertically or horizontally. So I went about building my own function for it. This is what I got:

function flipImage($image) {
    $width  = imagesx($image);
    $height = imagesy($image);

    $out = imagecreatetruecolor($width, $height);

    for($i = 0; $i < $width; $i++) {
        // Copy the image strip going left to right
        imagecopy($out, $image, $width - $i, 0, $i, 0, 1, $height);
    }

    //$out should now hold our flipped image
    return $out;
}

It works as I expected it to, but for some reason the returned image ($out) has a black background instead of a transparent one.

Is there any way to get the returned image to have a transparent background like the source image was?

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